Making cheap hour meter for my CNC 

Some time ago my spindle's brushes went out. This stopped the spindle, broke the bit and ruined the workpiece.
It could have damaged my CNC.
So I need a way to keep track of the total working time of my spindle and my CNC as a whole, so I know when to replace "consumables" and perform maintenance.
Here is how to make an hour meter for a CNC whose 110-220V spindle is controlled by the CNC ( = you don't switch it ON and OFF manually). If you have a manually started spindle check this wiring diagram instead: images-na.ssl-...
Oh yes, all this costs less than 15 bucks if you have old power sockets laying around.
Jayron JR-HM009 110-220V hour meter: amzn.to/2HfqUDe
My CNC is a EuroMakers Aureus 3X, similar to a Shapeoko or X-Carve.